It was a sarcastic Facebook comment during an argument about a video game. And, according to the father of 19-year-old Justin Carter, it was enough to land his son behind bars for months, facing the possibility of years in prison.

Carter, who is currentlyon suicide watch in Comal County Jail near San Antonio, Texas, has been locked up since February. He faces a charge of making terroristic threats, a felony that could theoretically bring a sentence of up to eight years.

"He's very depressed. He's very scared and he's very concerned that he's not going to get out," Jack Carter, Justin's father, told CNN on Tuesday. "He's pretty much lost all hope."

In February, Justin, then 18, and a friend were arguing on Facebook with someone else over the online video game "League of Legends."

"Someone had said something to the effect of 'Oh you're insane. You're crazy. You're messed up in the head,'" Jack Carter told CNN affiliate KVUE in Austin. "To which he replied 'Oh yeah, I'm real messed up in the head. I'm going to go shoot up a school full of kids and eat their still-beating hearts.'"

According to court documents, Justin wrote "I'm f---ed in the head alright. I think I'ma (sic) shoot up a kindergarten and watch the blood of the innocent rain down and eat the beating heart of one of them."

Facebook comment joke or threat?

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Dad: Jailed Facebook teen 'lost hope'

Jack Carter said his son followed the claim with "LOL" and "J/K" -- indicating that the comment wasn't serious.

But someone else -- Carter says a woman in Canada -- noticed the comment and reported it to authorities. Coming two months after the deadly shootings at an elementary school in Newtown, Connecticut, the report wasn't taken lightly. According to court documents, Carter lived less than a half-mile from an elementary school in New Braunfels, Texas.

A search warrant was issued on February 13 and, a week later, a judge issued a warrant for his arrest.

"I thought it was a joke," Jack Carter told CNN. "I couldn't believe the person that called me. I kept telling them they have to be kidding. When I realized he wasn't, I literally broke down crying."

A judge set bond for Justin Carter at $500,000, meaning that 10% of that, or $50,000, would have to be posted to get him out of jail while he awaits trial. His lawyer, Donald H. Flanary III, says that's far more than his family can afford.

"It's outrageous," Flanary, who is working the case for free, told CNN Tuesday. "I've represented murderers and their bond was $150,000."

Flanary said he planned to meet with Justin Carter Tuesday afternoon and ask a judge for the bond to be reduced. He said police didn't find any weapons or other items to suggest that Justin's comment was serious, but that, "in the times we're living in, it was kind of a perfect storm."

"The law enforcement, the sheriff's department, the district attorney's office -- nobody wants to be the one that let him go," Flanary said. "They don't think about the person or the crime or the lack of crime ... they don't want to take responsibility for something happening in the future."

A spokeswoman for the police department in Austin, where Justin was originally jailed, referred a request for comment and arrest documents to neighboring New Braunfels Police. A police department spokesman there did not immediately respond to a similar request.

Meanwhile, people have come together online to support the jailed teen.

"Too many teenagers are being arrested, jailed and having their lives forever altered because of anti-terrorism laws and investigations that impede their 1st Amendment right to freedom of speech," reads the petition.

Jack Carter says that, as a parent, he understands why authorities are so vigilant about threats of school violence.

"I definitely see the need to investigate such claims. Absolutely," he said. "But at some point during the investigation there has to be some common sense."